My understanding is that as these sorts of virus's mutate they do tend to get weaker.

There is I believe still one main strain of the virus, but I thought it worth having a separate thread to chart the development of strains.
There is a bit here on the New Scientist. Generally a reliable source:
https://www.newscientist.com/article/2236544-coronavirus-are-there-two-strains-and-is-one-more-deadly/

There was a post but I cannot find it about there being 3 strains, A B and C, if anyone can remember it please post it.

<cron order>

Coronavirus now has two strains, and you can get both | Al Arabiya English
https://english.alarabiya.net/en/News/world/2020/03/06/Coronavirus-now-has-two-strains-and-you-can-get-both

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Coronavirus mutates into 40 strains. How this changes the pandemic outlook: Experts | Al Arabiya English
https://english.alarabiya.net/en/features/2020/03/27/Coronavirus-mutates-into-40-strains-How-this-changes-the-pandemic-outlook-Exp

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Coronavirus: How scientists are tracking 8 strains of SARS-CoV-2 virus
https://www.usatoday.com/story/news/nation/2020/03/27/scientists-track-coronavirus-strains-mutation/5080571002/

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A-B-C

Coronavirus mutated into three distinct strains as it spread across the world | Metro News
https://metro.co.uk/2020/04/10/coronavirus-mutated-three-distinct-strains-spread-across-world-12536852/?ITO=squid?ito=cbshare

Early research indicates the coronavirus has mutated, similar to SARS - MarketWatch
https://www.marketwatch.com/story/early-research-indicates-the-coronavirus-has-mutated-similar-to-sars-2020-05-05

Study identifies six different "types" of COVID-19
https://www.msn.com/en-us/health/medical/study-identifies-six-different-types-of-covid-19/ar-BB179KSE